1. Field of the Invention
The present invention relates to a musical tone signal generating apparatus having a performance play capability which enables concurrent generation of musical tone signals having different voices assigned to a plurality of parts on the basis of a set of performance information. The present invention also relates to a computer program for the apparatus.
2. Description of the Related Art
Conventionally, there has been an electronic musical instrument which offers voice play mode and performance play mode for use in user's keyboard performance. Details on the electronic musical instrument are described from page 60 to page 73 of “Instructions on MOTIF ES” offered by Yamaha Corporation.
On this conventional electronic musical instrument, performance information brought on the basis of performance on a keyboard provided for the body of the electronic musical instrument and information brought on the basis of operations of various controllers is sent to a tone generating portion as MIDI massage. In the voice play mode, a set of performance information brought from the keyboard causes the tone generating portion to generate only one musical tone signal having a voice (tone color) which is selected by a user from among a plurality of voices prior to his performance on the keyboard. In the performance play mode, on the other hand, a set of performance information brought from the keyboard causes the tone generating portion to concurrently generate musical tone signals having different voices which compose layers having a plurality of parts. Each of the voices is assigned to a part, respectively. In other words, a set of musical tone signals having various voices assigned to a plurality of parts respectively is concurrently generated in response to a set of performance information. In this specification, a “performance” indicates a set of different voices (e.g., a set of four voices at the maximum). The user chooses one of the “performances” prior to his performance on the keyboard. In the performance play mode, therefore, a key depression by the user causes concurrent generation of a plurality of musical tone signals having various tone colors, resulting in enriched musical tones to be generated.